It is already known in the prior art to prepare slightly or highly superalkalinized sulfonates from sulfonic acids obtained by the sulfonation of different alkylaryl hydrocarbons and of an excess of alkaline earth base.
The alkylaryl hydrocarbons subjected to the sulfonation reaction result from alkylation by the Friedel-Crafts reaction of different aryl hydrocarbons, particularly aromatic, by two different types of olefin:
branched olefins resulting from the oligo-polymerization of propylene to C.sub.15 to C.sub.40 hydrocarbons, particularly the tetra polymer of propylene dimerized into a C.sub.24 olefin, and PA1 linear olefins that result from the oligo-polymerization of ethylene to C.sub.14 to C.sub.40 hydrocarbons. PA1 (a) the isomerization of a linear mono-alpha olefin containing between 14 and 40 carbon atoms to produce a linear mono-olefin containing a molar proportion of between 0 and 13% of alpha olefin, PA1 (b) the alkylation, by the Friedel-Crafts reaction, of an aryl hydrocarbon other than benzene by the linear mono-olefin.
Thus European Patent No. 1.318 to the company Exxon, published in 1981, describes superalkalinized mono alkyl orthoxylene sulfonates and mono alkyl toluene sulfonates resulting from the alkylation of the corresponding aromatic hydrocarbons by a mixture of branched olefins comprising a maximum proportion of 30% of linear olefin.
Furthermore, French Patent No. 2.564.830 to the company Orogil, the former name of the Assignee, and whose corresponding application was published in 1985, and which corresponds to U.S. Pat. No. 4,764,295 describes alkylaryl sulfonates of alkaline earth metals resulting from alkylation by a linear olefin.
In both cases, the alkylation reaction takes place in the presence of a Friedel-Crafts catalyst with a high excess of moles of the aryl hydrocarbon with respect to those of the olefin, to obtain, after recycling said excess, the corresponding mono alkylaryl hydrocarbon.